HIV (Human-Immunodeficiency-Virus) starts out when it is sexually transmitted, blood to blood, tattos (needles not desposed of, continuous use), sharing needles, mother to baby, and body piercing (needles not desposed of; continuous use). These can all infect you with the HIV virus. Mosquitoes don't carry HIV, neither can you get it from a pool. HIV can only live in these following fluids: Blood, Breast Milk, sperm/semen, and vaginal fluid. That is all. It starts out when it attacks the T helper cells, a bunch of cells that tell B helper cells to make Antibodies. (This is the Immune system.) When HIV virus attacks it, it tells the T helper cells to make more HIVs. The B helper cells no longer produce antibodies, leaving your body vunerable for diseases. Without antibodies, your body has no protection against germs. You cannot tell if a person is HIV positive. HIV long term can develop into AIDS, which your body can get uncurable, rare diseases that are fatal. Such as Sarcosi's sarcoma (a rare type of cancer). There a symptoms that go along with AIDS, but are not listed here. Please go to "www.virtualkid.com" and click health on the toolbar. There you will find this and other STDs.